1. Field of the Invention
The present invention relates to a gallium nitride group compound semiconductor represented by a general formula Al.sub.x Ga.sub.y In.sub.1-x-y N (0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1, 0.ltoreq.x+y.ltoreq.1), and to a method for manufacturing such a semiconductor. In particular, the present invention relates to a method for manufacturing a gallium nitride group compound semiconductor in which an epitaxial lateral overgrowth (ELO) method is used to form a layer on a substrate.
2. Description of the Related Art
A gallium nitride group compound semiconductor is a direct-transition-type semiconductor having a wide emission spectrum range from ultraviolet to red, and is applied to light-emitting devices such as light-emitting diodes (LEDs) and laser diodes (LDs). The gallium nitride group compound semiconductor is, in general, formed on a sapphire substrate.
However, in the above-described conventional technique, when a layer of a gallium nitride group compound semiconductor is formed on a sapphire substrate, a crack and/or warpage is generated in the semiconductor layer due to a difference in thermal expansion coefficient between sapphire and the gallium nitride group compound semiconductor, and dislocations are generated in the semiconductor layer due to misfit, resulting in degraded device characteristics.